<form action="?action=logout"  id="logoutform" name="loginform" method="post">
    <table align="right">
        <tr>
            <td>Usuario:</td>
            <td align="left"><label><?echo $_SESSION["username"]?></label></td>
        </tr>
        <tr>
            <td></td>
            <td align="right"><input type="submit" name="logout" value="logout" /></td>
        </tr>
    </table>
</form>'